One known full-parallax image display system that provides selectable viewpoints and presents an image of an object as seen from a viewpoint of a user is, for example, the IP (Integral Photography) 3D-image system developed by NHK (Japan Broadcasting Corporation).
FIG. 1 illustrates an example of the IP 3D-image system.
In the IP 3D-image system, a camera (video camera) 2 captures an image of an object through a lens array 1.
As shown in FIG. 2A in plan view and FIG. 2B in cross-sectional view, the lens array 1 has multiple microlenses disposed in a plane. The camera 2 captures the image of the object through each of the lenses.
In the IP 3D-image system, the image captured by the camera 2 is displayed on a display apparatus 3, such as a liquid crystal display. A lens array 4 having the same structure as the lens array 1 is disposed over the front face of a display screen of the display apparatus 3. A user may see the image displayed on the display apparatus 3 through the lens array 4. Thus, the user is able to view the image of the object from a certain viewpoint.
This means that the image captured by the camera 2 is a combination of image elements (referred to as microlens image-elements hereinafter) of the object seen through the microlenses of the lens array 1. Thus, the image displayed on the display apparatus 3 is a combination of the microlens image-elements. The combination of the microlens image-elements viewed from a certain viewpoint through the lens array 4 having the same structure as the lens array 1 forms an image of the object seen from that particular viewpoint. Such an image is formed of the microlens image-elements seen through the microlenses of the lens array 4, and each of the microlens image-elements includes pixels.
Accordingly, the IP 3D-image system presents an image that can be viewed from the actual viewpoint of the user.
To briefly (or theoretically) describe the IP 3D-image system, an image of an object as seen from a certain viewpoint is a combination of microlens image-elements. The microlens image-elements are gathered by the microlenses of the lens array 4, and include pixels that form the overall image of the object.
This means that the image resolution presented to a user depends on the microlenses of the lens arrays 1 and 4. However, there are limits to reducing the size of the microlenses and also to the number of the microlenses included in each of the lens arrays 1 and 4. This leads to difficulties in providing users with images having high spatial resolution.
Specifically, in the IP 3D-image system, the product of the number of the selectable viewpoints multiplied by the spatial resolution value of an image of one screen (one frame or one field) cannot exceed the spatial resolution value in the display apparatus 3. For this reason, increasing the viewpoints may lead to deterioration of the spatial resolution of an image.